What are best practices to override complete sections using docker-compose?

Question

The docker-compose.override contains:

volumes:
  - ./a:/path/to/a

The docker-compose:

volumes:
  - a:/path/to/a

When docker-compose up is run the override overwrite the ./a overwrites the a.

When a new volume is added to docker-compose, the override will try to mount is as well.

docker-compose.override

volumes:
  - ./a:/path/to/a

The docker-compose:

volumes:
  - a:/path/to/a
  - b:/path/to/b

How to prevent that the override will use volumes that are defined in the docker-compose file?

When docker-compose.override contains

volumes:
  - a:/path/to/a
  - .b:/path/to/b

the b is still mounted...

Answer 1

According to this documentation it does not seem to be possible to override complete sections in docker-compose by using different docker-compose files.

If both files are present on the same directory level, Compose combines the two files into a single configuration.

The configuration in the docker-compose.override.yml file is applied over and in addition to the values in the docker-compose.yml file.